High Catalytic-Activity CuNiM Catalysts Via Combustion Method For Morpholine Synthesis

Morpholine (Mp) as a typical heterocyclic compound has great industrial importance and a wide range of applications. It can be functionalized as a kind of chemical intermediate in drug/pesticide discovery and in rubber/textile industries. Because of its good biodegradability, morpholine and its derivatives have been used in the synthesis and preparation of new drugs, with a wide application prospect. At present, the major method used for producing morpholine is catalytic aminolysis of diethylene glycol. And the low activity of the catalysts is the main problems of this method. So it is necessary to study of the catalysts.In this paper, with ethylene glycol as the fuel, copper and nickel as the main component, CuxNiyO/Al2O3 catalysts were prepared by combustion method with lanthanum and without lanthanum in it. The catalysts were characterized by XRD、SEM-EDS、TPR、XPS、N2 adsorption and N2O titration. Results showed that copper preserved a relative small crystallite size and high dispersion in spite of high metal contents by using combustion synthesis technique. The high dispersion and close contact of copper with other species exhibited a high degree of synergistic effect, leading to the high conversion of DEG and selectivity of morpholine. Addition of La element facilitated the formation of surface defects, and thus inhibited the severe aggregation of copper nanocrystalite during calcination process as well as at higher reaction temperatures. As a result, the highest conversion of DEG and morpholine selectivity of the La-loaded Cu-NiO/Al2O3 catalyst prepared by combustion method reached up to 98.2% and 94.7% at 230 ℃ and 1.7 MPa, respectively. Thermal stability tests showed that the morpholine selectivity of the combustion-prepared catalysts still retained 93.2% after reaction of 3 hours at 290 ℃. The value was 26.7% higher than that on impregnation-prepared Cu-NiO catalysts under similar experimental conditions.With ethylene glycol as the fuel, copper and nickel as the main component, Cu-NiO@γ-Al2O3 catalysts were prepared by combustion method. And then compared the catalysts prepared by combustion method with those by impregnation method on the production capacity. Furthermore the effect of the doping with Zn、Mg、La、Al elements on the thermostability of catalysts were investigated. The catalysts were characterized by XRD、SEM and TPR. Results showed that compared with the catalysts prepared by impregnation method, those by combustion method remained better dispersion and smaller crystal size. And then the highest yield of morpholine on Cu-NiO@γ-Al2O3 catalysts can be 93% much higher than that on catalysts prepared by combustion method. The addition of Zn、Mg、La、Al elements can enhanced the thermostability of the catalysts. The catalysts with Zn in it showed the best thermostability. Ather the higt temperature experiment, the yield of morpholine decreased from 94% to 93%. At last, the age of catalysts was investigated, results showed that after 60 hours reaction, the conversion of DEG decreaced from 98% to 97%, the selectivity of morpholine changed from 95% to 93%, showed a good stability.